Interleukin-1 Receptor Type 1 Is Essential for Control of Cerebral but Not Systemic Listeriosis

Listeria monocytogenes may infect the central nervous system and several peripheral organs. To explore the function of IL-1 receptor type 1 (IL-1R1) in cerebral versus systemic listeriosis, IL-1R1−/− and wild-type mice were infected either intracerebrally or intraperitoneally with L. monocytogenes. After intracerebral infection with various numbers of attenuated Listeria, IL-1R1−/− mice succumbed due to an insufficient control of intracerebral Listeria, whereas all wild-type mice survived, efficiently restricting growth of Listeria. IL-1R1−/− mice recruited increased numbers of leukocytes, especially granulocytes, to the brain compared with wild-type mice. In contrast, both IL-1R1−/− and wild-type mice survived a primary and secondary intraperitoneal infection with Listeria without differences in the hepatic bacterial load. In addition, both strains developed similar frequencies of Listeria-specific CD4 and CD8 T cells after primary and secondary intraperitoneal infection. However, an intraperitoneal immunization before intracerebral challenge infection neither protected IL-1R1−/− mice from death nor reduced the intracerebral bacterial load, although numbers of intracerebral Listeria-specific CD4 and CD8 T cells and levels of inducible nitric oxide synthase, tumor necrosis factor, and interferon-γ mRNA were identical in IL-1R1−/− and wild-type mice. Collectively, these findings illustrate a crucial role of IL-1R1 in cerebral but not systemic listeriosis.